The present invention is related generally to transducers, i.e., devices which transform energy received of one kind to energy transmitted of a second kind. The invention relates more specifically to a transducer which responds to mechanical or acoustic input energy signals and transforms the information contained in the mechanical or acoustic signals into optical signals.
Recently, efforts have been expended in many technological areas to determine the possibility of utilizing light energy in place of traditional electrical energy to perform a wide variety of functions. One area of considerable importance in which significant progress has been made toward the use of light instead of electrical signals is in communications. Here, optical fibers in which light is retained by total internal reflection have been utilized to convey frequency multiplexed signals at relatively high efficiencies. The primary purpose for looking to light energy for use in communications is that by such frequency multiplexing techniques, a significantly greater amount of information may be carried on a single beam of light than on an electrical signal because of the greater frequency range over which such multiplexing may take place. Presently, nearly all information which is carried on such an optical communications link is initially perceived by standard electrically operated components, such as microphones. The electrical signals are then applied to electrooptic or similar devices to modulate various wavelength components of the light beam for transmission. Obviously, this electrical to optical energy transfer is accomplished at a loss in overall efficiency and greatly increases the cost and complexity of any system employing an optical medium for transmission purposes.
The present transducers which are utilized to perceive information contained in an environment are generally electrical in nature and are affected by all of the problems which customarily affect the operation of electrical devices. For example, electromagnetic interference (EMI) can strongly affect the performance of information carrying or generating electrical components and systems whereas light is impervious to EMI. Conversely, optical communications system components can be fabricated entirely of non-metallic materials. Therefore, such optical communications systems components do not disturb local magnetic fields thereby making the presence of such components difficult to detect. Electrical transducer devices necessarily have contacts therein. These contacts are susceptible to wear, to the formation of arcs therebetween, and to shorting. These characteristics of electrical transducers at least hinder the use of such devices in many environments. For example, where the environment contains high humidity and/or hazardous atmospheres, special precautions must be taken to prevent catastrophic results.